The present invention relates to a circuit for driving a heating resistor of a lamp, a heater or the like, and more particularly to a heating resistor driving circuit in which current surge is prevented from flowing through the heating resistor at the beginning of heating.
Excitation or driving of heating resistors is started by turning on a switch connected in series to the heating resistor. Such a heating resistor usually has a relatively low resistance which increases as heat is generated. In particular, immediately after the turning on of the switch (SW), a relatively high current spike (IL), such as shown in FIG. 4, tends to flow through the resistor.
Current spiking causes a drop of working voltage of a power source, resulting in operational errors of circuits, such as operational circuits, actuated by the power source. Instruments or devices including a large capacity power source to prevent the occurrence of current spiking can be bulky. To prevent effectively the occurrence of current spiking, the heating resistor has been preheated with a small amount of current. However, this approach has resulted in large power consumption.